In order to change the inclination of a mat disposed upon a bed, a tiltable mat supporting device has been used, in which a supporting member for the mat is rotatably mounted upon a longitudinal shaft provided upon the bed frame. The supporting member is mechanically turned upon the shaft or is turned by inserting an airbag having a triangularly-shaped section between the mat and the bed frame.
The former system is provided with a large-scale driving device for inclining the mat supporting member. Furthermore, it is necessary to provide a safety device such as a stopper for the rotation of the mat supporting member at a predetermined position. Therefore, the system is complicated in construction which causes an increase in the manufacturing cost thereof. In this system, when the mat is inclined at a relatively large angle, the mat may also slip off the airbag or the patient disposed within the bed may fall off the mat.